Filter Sheet Media and Method for Manufacturing a Filter Sheet Media

Abstract

A filter sheet media (1) for air/gas filtering applications fulfilling the criteria of standard EN779:2012 class M6 filter media, the filter sheet media (1) comprises: a first group of glass fibers (20) having a fiber diameter in a range of greater or equal to 6 μm up to 20 μm; a second group of glass fibers (30) having a fiber diameter in a range of 0.2 μm to less than 6 μm; a binder (40); the second group of glass fibers (30) have a fiber distribution gradient over the thickness (13) of the filter sheet media (1) so that the second group of glass fibers (30) are distributed through the thickness (13) of the filter sheet media (1), the filter sheet media (1) having more second group of glass fibers (30) near the first surface (11) than the second surface (12). Also disclosed is a method for manufacturing.

Claims

1. A filter sheet media (1) for air and gas filtering applications, the filter sheet media (1) comprises: a first group of glass fibers (20) having a fiber diameter in a range of greater a or equal to 6 μm up to 20 μm; a second group of glass fibers (30) having a fiber diameter in a range of 0.2 μm to less than 6 μm; a binder (40) for adhering the first group of glass fibers (20) to each other and further adhering the second group of glass fibers (30) to the first group of glass fibers (20); wherein the filter sheet media (1) has a first surface (11) and a second surface (12) and a thickness (13) in a direction perpendicular to the first surface (11) and the second surface (12), wherein the filter sheet media (1) fulfils at least criteria of standard EN779:2012 class M6 filter media; wherein the first group of glass fibers (20) comprises from 60 wt % to 90 wt % of the fiber content of the filter sheet media (1); wherein the second group of glass fibers (30) comprises from 10 wt % to 40 wt % of the fiber content of the filter sheet media (1), and have a fiber distribution gradient over the thickness (13) of the filter sheet media (1) so that the second group of glass fibers (30) are distributed through the thickness (13) of the filter sheet media (1), and the filter sheet media (1) has more second group of glass fibers (30) near the first surface (11) than the second surface (12).

2. A filter sheet media (1) according to claim 1, wherein the second group of glass fibers (30) are distributed over the thickness (13) direction in the fiber distribution gradient range of from 1:1.5 to 1:10, preferably in a range of from 1:1.5 to 1:6.

3. A filter sheet media (1) according to claim 1 or 2, wherein the second group of glass fibers (30) are distributed over the thickness (13) direction in the fiber distribution gradient of a linear, exponential, logarithmic or other curved manner.

4. A filter sheet media (1) according to claim 1, wherein the glass fibers in the filter sheet media (1) consist of the first group of glass fibers (20) and the second group of glass fibers (30).

5. A filter sheet media (1) according to claim 1, wherein the filter sheet media (1) comprises the first group of glass fibers (20), the second group of glass fibers (30) and other fibers.

6. A filter sheet media (1) of claim 1, wherein the fiber diameter of glass fibers (20) of the first group is more than 2 μm larger than the fiber diameter of the glass fibers (30) of the second group.

7. A filter sheet media (1) of claim 1, wherein the first group of glass fibers (20) are chopped, cut or stapled to have even fiber length in a range of 3 mm to 20 mm.

8. A filter sheet media (1) of claim 1, wherein the filter sheet media (1) is adapted to fulfil criteria of standard EN779:2012 class F7 filter sheet media (1) wherein the first group of glass fibers (20) is from 60 to 70 wt % of the fiber content of the filter sheet media (1), wherein the second group of glass fibers (30) is from 30 to 40 wt % of the fiber content of the filter sheet media (1), and wherein the binder (40) is from 10 to 20 wt % of the total weight of the filter sheet media.

9. A filter sheet media (1) of claim 1, wherein the filter sheet media (1) comprises binder (40) 10 to 20 wt % of the total weight of the filter sheet media (1).

10. A filter sheet media (1) of claim 1, wherein the binder (40) comprises one or more components having an effect on binding properties, a strength of the filter sheet media, hydrophobic/hydrophilic properties, retention properties or foam forming properties.

11. A filter sheet media (1) of claim 1, wherein the binder (40) is selected from group of acrylates, such as styrene acrylate, acrylic acid resin, or ethylene vinyl acetate, polyvinyl acetate, polyvinyl alcohol, starch, styrene butadiene, urea formaldehyde resin, melamine formaldehyde resin, polyurethanes, polycarbonates, saturated polyesters, unsaturated polyesters, polyterpenes, furan polymers, polyfurfural alcohol, polyamides, polyimides, polyamidimides, polyamidoamines, copolymers thereof, and combinations thereof.

12. A method for manufacturing a filter sheet media (1) for air and gas filtering applications, wherein the filter sheet media (1) fulfils at least criteria of standard EN779:2012 class M6 filter media, the method comprising: preparing a furnish for the filter sheet media (1) comprising: a first group of glass fibers (20) having a fiber diameter in a range of greater or equal to 6 μm up to 20 μm, an amount of the first group of glass fibers (20) being from 60 to 90 wt % of the fiber content of the filter sheet media (1), a second group of glass fibers (30) having a fiber diameter in a range of 0.2 μm to less than 6 μm, an amount of the second group of glass fibers (30) being from 10 to 40 wt % of the fiber content of the filter sheet media (1), a binder (40) for adhering the first group of glass fibers (20) to each other and further adhering the second group of glass fibers (30) to the first group of glass fibers (20), providing the furnish as a foam suspension to a web forming machine (5, 6), to be formed as a web of filter sheet media (1) having a first surface (11) and a second surface (12) and a thickness (13) in a direction perpendicular to the first surface (11) and the second surface (12), and wherein the second group of glass fibers (30) are distributed by a foam laid process so that the second group of glass fibers (30) forms a fiber distribution gradient over the thickness (13) direction of the filter sheet media (1), the filter sheet media (1) having more second group of glass fibers (30) near the first surface (11) than the second surface (12).

13. A method for manufacturing the filter sheet media (1) of claim 12, wherein formation of the web is done by using a single layer inclined twin wire former (5).

14. A method for manufacturing the filter sheet media (1) of claim 12, wherein the gradient structure is formed by using multilayer headbox (6) and a former.

15. A method for manufacturing the filter sheet media (1) of claim 12, wherein the second group of glass fibers (30) are distributed over the thickness (13) direction in a fiber distribution gradient of a linear, exponential, logarithmic or other curved manner by adjusting the foam properties of the furnish.

16. A method for manufacturing the filter sheet media (1) of claim 12, wherein foam properties are being controlled with a foam forming agent and mixing parameters of the furnish.

17. A method for manufacturing the filter sheet media (1) of claim 12, wherein the filter sheet media (1) is adapted to fulfil criteria of standard EN779:2012 class F7 filter sheet media, wherein the first group of glass fiber (20) is from 60 to 70 wt % of the fiber content of the filter sheet media (1); wherein the second group of glass fibers (30) is from 30 to 40 wt % of the fiber content of the filter sheet media (1); and wherein the binder (40) is from 10 to 20 wt % of the total weight of the filter sheet media (1).

Description

BRIEF DESCRIPTION OF DRAWINGS

[0038] In the following, the disclosure will be described with reference to the accompanying exemplary, schematic drawings, in which:

[0039] FIG. 1 illustrates a filter sheet media according to an embodiment of the disclosure,

[0040] FIG. 2 illustrates a filter sheet media according to another embodiment of the disclosure,

[0041] FIG. 3 illustrates a schematic embodiment of a filter sheet media production machine, and

[0042] FIG. 4 illustrates a schematic embodiment of another filter sheet media production machine.

DETAILED DESCRIPTION

[0043] FIG. 1 depicts schematically a filter sheet media 1 for air and gas filtering applications. The filter sheet media comprises at least the following components: a first group of glass fibers 20 (not explicitly depicted on the FIG. 1) having a fiber diameter in a range of greater or equal to 6 μm up to 20 μm; a second group of glass fibers 30 having a fiber diameter in a range of 0.2 μm to less than 6 μm; a binder 40 (not explicitly depicted on the FIG. 1) for adhering the first group of glass fibers 20 to each other and further adhering the second group of glass fibers 30 to the first group of glass fibers 20; wherein the components have formed as a filter sheet media 1 having a first surface 11 and a second surface 12 and a thickness 13 in a direction perpendicular to the first surface 11 and the second surface 12, the filter sheet media 1 fulfils at least criteria of standard EN779:2012 class M6 filter media. The filter sheet media composition comprises: the first group of glass fibers 20 from 60 wt % to 90 wt % of the fiber content of the filter sheet media 1; the second group of glass fibers 30 from 10 wt % to 40 wt % of the fiber content of the filter sheet media; and the second group of glass fibers 30 have a fiber distribution gradient over the thickness 13 of the filter sheet media 1 so that the second group of glass fibers 30 are distributed through the thickness 13 of the filter sheet media 1, the filter sheet media 1 having more second group of glass fibers 30 near the first surface 11 than the second surface 12. The first group of glass fibers 20 and binder 40 are not explicitly depicted in FIG. 1 to enhance the visual presentation of fiber distribution gradient of second group of glass fibers 30. Thus, all the small fibers shown in FIG. 1 represent the fibers of the second group of glass fibers. As can also be noted, the first surface 11 is in this embodiment the lower surface, normally referring to the wire side of a produced web or sheet.

[0044] FIG. 2 depicts schematically a filter sheet media 1 for air and gas filtering applications. The filter sheet media comprises at least the following components: a first group of glass fibers 20 (not shown in FIG. 2) having a fiber diameter in a range of greater or equal to 6 μm up to 20 μm; a second group of glass fibers 30 having a fiber diameter in a range of 0.2 μm to less than 6 μm; a binder 40 (not shown in FIG. 2) for adhering the first group of glass fibers 20 to each other and further adhering the second group of glass fibers 30 to the first group of glass fibers 20; wherein the components have formed as a filter sheet media 1 having a first surface 11 and a second surface 12 and a thickness 13 in a direction perpendicular to the first surface 11 and the second surface 12, the filter sheet media 1 fulfils at least criteria of standard EN779:2012 class M6 filter media. The filter sheet media composition comprises: the first group of glass fibers 20 from 60 wt % to 90 wt % of the fiber content of the filter sheet media 1; the second group of glass fibers 30 from 10 wt % to 40 wt % of the fiber content of the filter sheet media; and the second group of glass fibers 30 have a fiber distribution gradient over the thickness 13 of the filter sheet media 1 so that the second group of glass fibers 30 are distributed through the thickness 13 of the filter sheet media 1, the filter sheet media 1 having more second group of glass fibers 30 near the first surface 11 than the second surface 12. The first group of glass fibers 20 and binder 40 are not explicitly depicted in FIG. 2 to enhance the fiber distribution gradient of second group of glass fibers 30. Thus, all the small fibers shown in FIG. 2 represent the fibers of the second group of glass fibers 30. As can also be noted, the first surface 11 is in this embodiment an upper side, top surface, normally referring to the top side of a produced web or sheet.

[0045] FIG. 3 presents a device for utilizing the method for manufacturing the filter sheet media 1. As shown in FIG. 3 a single layer inclined (twin) wire former is used for the formation of the web. Fiber suspensions containing both the first group of glass fibers 20 and the second group of glass fibers 30 are first mixed and then guided on the wire where the gradient of second group of glass fibers is produced.

[0046] FIG. 4 present another device for utilizing the method for manufacturing the filter sheet media 1. As shown in FIG. 4 a multilayer headbox and a former is used for the formation of the web. Fiber suspensions containing the first group of glass fibers 20 and the second group of glass fibers 30 are fed as separate streams from the headbox to the former. Thus, the gradient of second group of glass fibers is obtained by layering the two suspensions.

EXAMPLES

[0047] In the following data table 1 it is shown results of experiments where different versions of filter sheet media samples have been produced and then tested. On the top row it is shown which sample is concerned and on rows there is the determined or measured properties. Experiments 1, 2 and 3 are according to the specs of initial inventive scope. On the right-hand columns there are comparative examples 1 and 2 of commercially available EN779:2012 class M6 filter medias. The following test standards have been used to measure the properties: [0048] Basis Weight: TAPPI Standard T410 [0049] Caliper: TAPPI Standard T411 [0050] Frazier: TAPPI Standard T 251 [0051] Penetration @ 0.3 μm: ASTM D2986 [0052] Tensile, Elongation: Tappi T494

TABLE-US-00001 TABLE 1 Results of Experiments Experi- Experi- Experi- Comparative Comparative Property Unit ment 1 ment 2 ment 3 Example 1 Example 2 First group of wt % 65 60 65 15 30 glass fibers Diameter of μm 10 10 10 6 6 first group of glass fibers Second group of wt % 35 40 35 83 70 glass fibers Diameter of μm 2.06 2.06 2.06 3.9 (53 wt %) 3.9-5.6 second group of 5.6 (30 wt %) glass fibers Binder wt % 13 13 13 10 8% gradient yes/no yes yes yes no no observed Basis Weight g/m.sup.2 55.8 59 70.3 69 67.3 Caliper μm 300 325 389 395 362 TAPPI T411 Density g/cm.sup.3 0.186 0.182 0.181 0.175 0.19 Frazier cfm 122 121 118 115 118 Penetration % 76.4 79.2 78.7 77 75.6 0.3μ @ 5.32 cm/s DP @ mm H.sub.2O 1.1 1.1 1 1.2 1.1 5.32 cm/s Meet the yes/no yes yes yes yes yes requirement for M6 Tensile MD Kg/15 mm 2.85 3.26 3.3 2.13 1.49 Tensile MD Kg/15 mm 1.88 1.14 2.1 0.94 0.47 after fold Elongation % 1.3 1.5 0.8 1.5 0.89 Stiffness MD mg 690 650 1390 800 1000

[0053] As can be noted, those samples having an observable gradient, wherein the second group of glass fibers are up to 40 wt % seem to produce many desired properties for a highly versatile filter sheet media. The experimental samples have higher tensile strength since there is a higher amount of first group of glass fibers, e.g., using a large amount of the first group of glass fibers gives the media a higher tensile strength. This is reflected in the table above, where the experimental samples have higher tensile strength than the comparative examples. Also, as an example, a variety of different basis weights can be used without adverse effects on the disclosed filter sheet media.

[0054] While the disclosure has been described herein by way of examples in connection with what are, at present, considered to be the most preferred embodiments, it is to be understood that the disclosure is not limited to the disclosed embodiments, but is intended to cover various combinations or modifications of its features, and several other applications included within the scope of the disclosure, as defined in the appended claims. The details mentioned in connection with any embodiment above may be used in connection with another embodiment when such combination is technically feasible.

REFERENCE NUMBERS IN FIGURES

[0055] 1 filter sheet media [0056] 11 first surface [0057] 12 second surface [0058] 13 thickness [0059] 20 first group of glass fibers [0060] 30 second group of glass fibers [0061] 40 binder [0062] 5 single layer inclined wire former [0063] 6 multilayer headbox